Costruire Siti Web

Good morning I have a Magento website (vers. 1.8.0.0) I would like to develop/enable a popup similar the one is on this site: [login to view URL] Inside this popup, which should be online on the first web page where a user arrives, a Mailchimp form will be integrated. Users will be able to sign up their email and they will receive a registration email with a discount coupon (a Mailchimp account already exists). During a user session the popup will never have to appear twice. If closed by the user, the popup will not appear again (on another web page). Thanks